Cerf

What's Changed
* Documentation update by crvernon in https://github.com/IMMM-SFA/cerf/pull/101
* Feature/package update by crvernon in https://github.com/IMMM-SFA/cerf/pull/105
* Remove whitebox dependency by crvernon in https://github.com/IMMM-SFA/cerf/pull/107
* Staging version 2.4.0 by crvernon in https://github.com/IMMM-SFA/cerf/pull/108


**Full Changelog**: https://github.com/IMMM-SFA/cerf/compare/v2.3.2...v2.4.0

- Use tempdir instead of named temp file for compatability with Windows paths

- Fix bug in which edge cases for coordinates that did not match for rounding approach. Now use spatial approach.

- Added feature to initialize power plant locations from coordinates instead of index which was only available when inheriting previous cerf output.

- Updated the minimum Python version for the package and actions to 3.9 per dependency requirement.

- Changed docs to thousands of km for interconnection cost variables https://github.com/IMMM-SFA/cerf/pull/92
- Reporting incorrect operation costs. There will be no effect to the siting result, but will influence operating cost reporting in the output. https://github.com/IMMM-SFA/cerf/pull/91

New parameter enabled named `operational_life_yrs` and is read in through the configuration file after lifetime.

**Description**: A separate parameter to allow for early retirement of power plants (i.e., not operating to their full expected life) and is set as the number of years after siting that the plant gets retired. This can account for expectations that some technologies will be forced to retire early in a future year.

This parameter will replace lifetime in determining future retirement within CERF. Lifetime will still be used to calculate other variables.